Congestive heart failure, characterized by an inability of the heart to pump a sufficient amount of blood, is a major worldwide health concern. In the United States alone, approximately 400,000 new cases are diagnosed annually (Gilum 1993). Congestive heart failure may arise from a variety of causes, including heart attacks, long-term high blood pressure, disease of the heart valves, or congenital heart defects. Patients with congestive heart failure are potential candidates for heart transplants, but there are not enough transplantable hearts available to satisfy the needs of each of these candidates.
A ventricular assist device (VAD) is a mechanical pump used to assist the heart in pumping blood through the body. VADs were originally designed for short-term use only, as a means to keep a patient alive until a heart transplant was available. However, in recent years VADs have begun to be used as a long-term therapy option for patients who are not heart transplant candidates. VADs partially relieve symptoms of severe heart failure such as shortness of breath and fatigue.